The goal of the Transgenic Mouse Core is to provide the investigators of each project with assistance in the[unreadable] design and production of genetically modified mice. To achieve this goal, the core will perform the following[unreadable] functions:[unreadable] Specific Aim 1. Design and construct transgenes and develop genotyping assays. Core personnel will[unreadable] consult with the project leaders regarding the goal for each proposed transgenic model. Appropriate DNA[unreadable] constructs will then be designed using optimal promoter and coding sequences. The required genomic or[unreadable] cDNA clones for the gene of interest will be acquired and cloned downstream from the desired promoter.[unreadable] Transgene DNA will be purified for microinjection, and genotyping assays will be designed and tested.[unreadable] Specific Aim 2. Generate transgenic founders via microinjection of transgene DNA. Fertilized eggs from the[unreadable] C57BL/6 strain of mice will be used for pro-nuclear injection of transgene construct DNA. Potentially[unreadable] transgenic offspring will be identified using genotyping assays developed in Specific Aim 1. Founder mice[unreadable] will be characterized for the ability to transmit the transgene to offspring. The number of independent[unreadable] chromosomal integration sites in each founder will be determined. Germline-competent mice, each with a[unreadable] transgene integrated at a single genomic locus, will be delivered to project leaders.[unreadable] Specific Aim 3. Assist in the characterization of transgenic mice. Quantitative reverse-transcriptase[unreadable] polymerase chain reaction (RT-PCR) assays will be designed to specifically detect transgene mRNAs and[unreadable] then used to determine the tissue distribution of transgene mRNA expression. If transgene expression is[unreadable] low, core personnel will assist the Project Leader in identifying reasons for low expression and optimizing[unreadable] transgene design to overcome the problem.[unreadable] Transgenic mice are increasingly used to address questions in aging and skeletal research. Experiments in[unreadable] transgenic mice allow investigators to determine whether phenomena observed in cell lines and primary cell[unreadable] cultures also occur in vivo. In addition, transgenic mice can be used to test hypotheses that cannot be[unreadable] convincingly addressed in any in vitro system. Thus timely and efficient production of transgenic mice is[unreadable] essential to the overall goal of the Program which is to improve the understanding of the pathophysiology of[unreadable] the bone fragility syndrome of osteoporosis and thereby rationalize and optimize its treatment.[unreadable]